Catalytic asymmetric synthesis of the central tryptophan residue of celogentin C
Steven L Castle1, G S C Srikanth
1Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah 84602, USA. scastle@chem.byu.edu
Abstract:
[reaction: see text] Chiral phase-transfer catalyst 5 containing an electron-deficient trifluorobenzyl moiety promoted the alkylation of glycine derivative 6 with propargyl bromide 7a in good yield and excellent ee. The resulting propargyl glycine 8 was converted to 14, the central tryptophan residue of Celogentin C, in two steps, with the Pd-catalyzed heteroannulation as the key transformation. This method promises to be an efficient route for the preparation of tryptophan derivatives possessing substitution on the indole ring.
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